To apply what this means to your crusher, operations produce the exact sizes in the reduction process that their market demands. In the past, quarries produced a range of single-size aggregate products up to 40 mm in size.
In practice, many jaw crushers are not fed to their designed capacity. This is because the subsequent processing plant does not have sufficient capacity to handle the volume of material that would be produced if the jaw crusher was working to capacity.
If you seek fewer fines, trickle feeding material into the jaw crusher could achieve this. But this would have an adverse effect on particle shape, and it also reduces throughput capacity, hindering the crushers efficiency.
Ideally, the feed rate should not be switched from choke to non-choke, as this can cause problems downstream at the secondary processing plant. In practice, many jaw crushers are fed in this intermittent fashion due to gaps in the delivery of feed material from the quarry.
The reduction ratio is then calculated by comparing the input feed size passing 80 percent versus the discharge size that passes 80 percent. The finer the closed-side setting, the greater the proportion of fines produced.
The closed-side setting of a jaw crusher helps determine the nip angle within a chamber, typically 19 to 23 degrees. Too large of an angle causes boiling in the crushing chamber. This is where the jaw plates cannot grip onto the rock, and it keeps slipping up and down, avoiding being crushed. The nip angle gets flatter as the machine is set tighter.
The settings on a jaw crusher are designed to produce material ideal for secondary crushing. The best particle shape is typically found in material that is about the same size as the closed-side setting.
Smaller sizes will contain a higher proportion of elongated particles because they have passed through the crusher without being touched. Larger sizes may also contain a higher proportion of elongated particles because they are further from the closed-side setting. This can cause bridging issues in downstream machines.
It is critical that a cone-type crusher be choke fed to produce the best product shape and quality. It is not as important in a jaw, as material is not generally stockpiled after the jaw. Because the cone is part of the secondary and tertiary stations, particle shape assisted by a choke-fed chamber is important because finished products are created in these stages.
Choke feeding is important for cone crushers because it maintains a good particle shape by facilitating an inter-particle crushing action. Trickle feeding is not the best option because it increases the proportion of flaky material in the crusher product, hindering its efficiency.
It is a good rule to maintain about 10 to 15 percent of material finer than the closed-side setting in the feed to assist crushing action. More than 10 to 15 percent will likely cause ring bounce due to the pressures in the chamber.
Its important to find the right liner for the feed gradation and desired product. If the liner is too large, feed material will drop too far in the chamber before being crushed. Too fine of a liner will prevent material from entering the chamber at all.
Monitoring the crushing force as registered through the load on the crusher motors, as well as the pressure on the hydraulic mantle adjustment mechanism, will give forewarning of crusher packing problems before they affect your efficiency.
Try to match the closed-side setting of the crusher to the top size of the product to be produced. If closing the circuit at 1 in. to produce a 1-in.-minus product, set the crusher at or near 1 in. or slightly below.
The initial impact is responsible for more than 60 percent of the crushing action, with the remainder made up of impact against an adjustable breaker bar and a small amount of inter-particle collision.
This is why it is vitally important that the feed arrangement to an impact crusher ensures an even distribution of feed material across the full width of the rotor. This will allow for even distribution of energy into the feed material and uniform wear patterns, ensuring consistent product gradation and power consumption.
Slower rotor speeds can be used as a means of reducing fines but may result in a product with more oversize or return than is desired. Slower rotor speeds are preferable as a means of minimizing the wear on crusher components, as well as for achieving less fines production and optimal product size.
The product grading from an impact crusher will change throughout the life of the wear parts, particularly the impact hammers or blow bars. As the profile of the hammer changes with increased wear, the product grading becomes coarser. Many modern impact crusher installations have a variable speed drive arrangement that allows an increase in the rotor speed to compensate for wear on the impact hammers.
In many impact crushers, a third curtain or crushing chamber can be added to increase reduction in every pass through the machine. This can be important in finer product applications where the third chamber can provide the desired output gradation. A third chamber that increases the reduction will also increase the power needs and, normally, the wear cost.
One tip to consider: Decreasing the gap between the hammers and impact curtain increases particle retention in the chamber. This increases the size reduction ratio, but it also reduces efficiency throughput capacity and increases fines production.
Follow the steps outlined in this article to achieve the best crushing efficiency for jaw, cone, gyratory and impact crushers and to ultimately increase profits and reduce fines production. By taking these steps, youre reducing the amount fines produced and adding dollars to your pocket.
The jaw crusher is mainly composed of a frame, a movable jaw assembly, a movable jaw, a fixed jaw, a triangular wheel, a flywheel, a bracket, a side guard, a discharge port adjusting device and a driving device. Because of its simple structure, easy manufacture, reliable operation and convenient maintenance, it has been widely used in crushing operations in metallurgy, chemical industry and mining industries.
In the jaw crusher, the ore is crushed and reduced to the required particle size. When the moving plate moves away from the fixed plate, the ore is sliding down freely from the upper portion of the crushing chamber to the discharge port under the action of gravity. During this process, the ore slides down along the surface of the jaw plate and causes sliding friction which makes the jaw plate be worn. Therefore, the abrasive wear is an important wear type caused by the squeezed ore.
When the ore is squeezed and ground under the huge mechanical force of the jaw plate, it is easy to form hard sharp edges and corners, and continual interaction between ore and the jaw plate makes the surface of the jaw plate appear very deep scratches, dense grooves and large-area deep pits. As a result, under the strong chiseling action, the jaw plate develops plastic deformation, metal rheology, brittle fracture and spalling, causing the material of jaw plate continuously to migrate and lose, and gradually become thinner. Therefore, chiseling wear is the main form of wear.
Jaw crusher has a large crushing force and fast running speed. Under the action of the huge impact and crushing stress, it withstands long-term and periodic contact fatigue load and is prone to fatigue crack. Therefore, fatigue spalling is also one of the causes of wear.
In order to protect the environment and improve working conditions, a water spray facility is installed on the site of the jaw crusher for dust suppression. At the same time, the water directly contacts the raft which accelerates the oxidation and corrosion of the raft and causes corrosion and wear of the raft.
The wear of the jaw plate presents complexity and diversity and is affected by factors such as materials, abrasives, environmental media, and relative motion. The value of the moving motion is usually reduced to solve the wear problems. In recent years, with the rapid development of computer technology, software simulation is used to comprehensively consider various factors that cause wear, and dynamically imitate of the crushing movement of the jaw plate, so as to more comprehensively analyze the wear rules of the jaw plate and finally reduce its wear rate.
In addition to the wear problem of the jaw plate, there are many other problems caused by parts and components can not be ignored. Next, we will introduce the failure analysis and troubleshooting of the jaw crusher.
4Check the tooth gap size of the tooth plate. If it does not meet the standard, the jaw plate must be replaced, and the relative position of the fixed jaw plate and the movable jaw plate should be adjusted to ensure that the tooth top is fixedly pressed against the tooth root to prevent displacement.
6It is non-bearing temperature rising, but the sealing sleeve of the movable jaw rubs with the end cap, which causes friction heating, or the double embedded cover of the frame bearing seat and the spindle rotate together, causing friction and heat.
6Replace the end cap and the sealing sleeve, or loosen the upper bearing cap of the end of the frame bearing housing which is overheated, press the fuse and the insert cover into the bearing housing groove, and then fix the bearing cover to eliminate the cover rotation.
Precision-machined, drop-forged, heat-treated Cr-Si-Mn-Mo SAE 4140 (42Cr, Mo4) steel eccentric shaft. The larger eccentricity of pitman shaft provides a motion that forces the material to the bottom of the jaw plate.
Spherical, self-aligning roller bearings, straight-bore pitman bearings and tapered-bore body bearings provide maximum strength to the pitman shaft and bearings for a long extended maintenance life.
The jaw crusher is one of the most indispensable and preferred machines because of its performance and durability. Depending on plant layout, jaw Crusher can be produced on wheels, skid-mounted or fixed to the concrete foundations.
In the quarry, crushing is handled in four potential stages: primary, secondary, tertiary and quaternary. The reduction of aggregate is spread over these stages to better control the product size and quality, while minimizing waste.
The primary stage was once viewed merely as a means to further reduce stone following the blast or excavation prior to secondary crushing. Today, primary crushing is viewed as more important within the balance of production and proper sizing needs. The size and type of the primary crusher should be coordinated with the type of stone, drilling and blasting patterns, and the size of the loading machine. Most operations will use a gyratory, jaw or impact crusher for primary crushing.
In the secondary and subsequent stages, the stone is further reduced and refined for proper size and shape, mostly based on specifications to produce concrete and asphalt. Between stages, screens with two or three decks separate the material that already is the proper size. Most secondary crushers are cone crushers or horizontal-shaft impact crushers. Tertiary and quaternary crushers are usually cone crushers, although some applications can call for vertical-shaft impact crushers in these stages.
A gyratory crusher uses a mantle that gyrates, or rotates, within a concave bowl. As the mantle makes contact with the bowl during gyration, it creates compressive force, which fractures the rock. The gyratory crusher is mainly used in rock that is abrasive and/or has high compressive strength. Gyratory crushers often are built into a cavity in the ground to aid in the loading process, as large haul trucks can access the hopper directly.
Jaw crushers are also compression crushers that allow stone into an opening at the top of the crusher, between two jaws. One jaw is stationary while the other is moveable. The gap between the jaws becomes narrower farther down into the crusher. As the moveable jaw pushes against the stone in the chamber, the stone is fractured and reduced, moving down the chamber to the opening at the bottom.
The reduction ratio for a jaw crusher is typically 6-to-1, although it can be as high as 8-to-1. Jaw crushers can process shot rock and gravel. They can work with a range of stone from softer rock, such as limestone, to harder granite or basalt.
As the name implies, the horizontal-shaft impact (HSI) crusher has a shaft that runs horizontally through the crushing chamber, with a rotor that turns hammers or blow bars. It uses the high-speed impacting force of the turning blow bars hitting and throwing the stone to break the rock. It also uses the secondary force of the stone hitting the aprons (liners) in the chamber, as well as stone hitting stone.
With impact crushing, the stone breaks along its natural cleavage lines, resulting in a more cubical product, which is desirable for many of todays specifications. HSI crushers can be primary or secondary crushers. In the primary stage, HSIs are better suited for softer rock, such as limestone, and less abrasive stone. In the secondary stage, the HSI can process more abrasive and harder stone.
Cone crushers are similar to gyratory crushers in that they have a mantle that rotates within a bowl, but the chamber is not as steep. They are compression crushers that generally provide reduction ratios of 6-to-1 to 4-to-1. Cone crushers are used in secondary, tertiary and quaternary stages.
With proper choke-feed, cone-speed and reduction-ratio settings, cone crushers will efficiently produce material that is high quality and cubical in nature. In secondary stages, a standard-head cone is usually specified. A short-head cone is typically used in tertiary and quaternary stages. Cone crushers can crush stone of medium to very hard compressive strength as well as abrasive stone.
The vertical shaft impact crusher (or VSI) has a rotating shaft that runs vertically through the crushing chamber. In a standard configuration, the VSIs shaft is outfitted with wear-resistant shoes that catch and throw the feed stone against anvils that line the outside of the crushing chamber. The force of the impact, from the stone striking the shoes and anvils, fractures it along its natural fault lines.
VSIs also can be configured to use the rotor as a means of throwing the rock against other rock lining the outside of the chamber through centrifugal force. Known as autogenous crushing, the action of stone striking stone fractures the material. In shoe-and-anvil configurations, VSIs are suitable for medium to very hard stone that is not very abrasive. Autogenous VSIs are suitable for stone of any hardness and abrasion factor.
Roll crushers are a compression-type reduction crusher with a long history of success in a broad range of applications. The crushing chamber is formed by massive drums, revolving toward one another. The gap between the drums is adjustable, and the outer surface of the drum is composed of heavy manganese steel castings known as roll shells that are available with either a smooth or corrugated crushing surface.
Double roll crushers offer up to a 3-to-1 reduction ratio in some applications depending on the characteristics of the material. Triple roll crushers offer up to a 6-to-1 reduction. As a compressive crusher, the roll crusher is well suited for extremely hard and abrasive materials. Automatic welders are available to maintain the roll shell surface and minimize labor expense and wear costs.
These are rugged, dependable crushers, but not as productive as cone crushers with respect to volume. However, roll crushers provide very close product distribution and are excellent for chip stone, particularly when avoiding fines.
Hammermills are similar to impact crushers in the upper chamber where the hammer impacts the in-feed of material. The difference is that the rotor of a hammermill carries a number of swing type or pivoting hammers. Hammermills also incorporate a grate circle in the lower chamber of the crusher. Grates are available in a variety of configurations. The product must pass through the grate circle as it exits the machine, insuring controlled product sizing.
Hammermills crush or pulverize materials that have low abrasion. The rotor speed, hammer type and grate configuration can be converted for different applications. They can be used in a variety of applications, including primary and secondary reduction of aggregates, as well as numerous industrial applications.
Virgin or natural stone processing uses a multi-stage crushing and screening process for producing defined aggregate sizes from large lumps of rock. Such classified final fractions are used as aggregates for concrete, asphalt base, binder and surface course layers in road construction, as well as in building construction. The rock is quarried by means of drilling and blasting. There are then two options for processing the bulk material after it has been reduced to feeding size of the crushing plant: mobile or stationary plants.
When stone is processed in mobile primary crushing plants, excavators or wheel loaders feed the rock into the crusher that is set up at the quarry face, gravel pit or in a recycling yard or demolition site. The crushed material is then either sent to the secondary/tertiary processing stage via stacking conveyors or transported by trucks. Some mobile crushers have an independent secondary screen mounted on the unit, effectively replacing a standalone screen.
The higher the compressive strength of rock, the higher also is its quality, which plays an important role particularly in road construction. A materials compressive strength is delineated into hard, medium-hard or soft rock, which also determines the crushing techniques used for processing to obtain the desired particle sizes.
The materials quality is influenced significantly by particle shape. The more cubic-shaped the individual aggregate particles are, the better the resulting particle interlock. Final grains of pronounced cubic shape are achieved by using several crushing stages. A cubicity showing an edge ratio of better than 1-to-3 is typical of high-quality final aggregate.
As the earths natural resources are becoming ever more scarce, recycling is becoming ever more important. In the building industry, recycling and reuse of demolition concrete or reclaimed asphalt pavement help to reduce the requirements for primary raw materials. Mobile impact and jaw plants are uniquely positioned to produce high-quality reclaimed asphalt pavement (RAP) and recycled concrete aggregate (RCA) for reuse in pavements, road bases, fill and foundations.
Use of RAP and RCA is growing dramatically as road agencies accept them more and more in their specs. But because RAP and RCA come from a variety of sources, to be specified for use by most departments of transportation they must be processed or fractionated and characterized into an engineered, value-added product. RCA or RAP are very commonly crushed and screened to usable sizes often by impact crushers and stored in blended stockpiles that can be characterized by lab testing for use in engineered applications.
Impact crushers are increasingly used for crushing recycling material. Impact crushers are capable of producing mineral aggregate mixes in one single crushing stage in a closed-cycle operation, making them particularly cost-effective. Different crusher units can alternatively be combined to process recycling material. A highly efficient method of processing recycling material combines crushing, screening and separation of metals. To produce an end product of even higher quality, the additional steps of washing to remove light materials such as plastics or paper by air classification and via electromagnetic metal separator are incorporated into the recycling process.
Mobile impact crushers with integrated secondary screens or without integrated screen used in conjunction with an independent mobile screen are ideal for producing large volumes of processed, fractionated RAP or RCA on a relatively small footprint in the plant. Mobile impactors are especially suited for RAP because they break up chunks of asphalt pavement or agglomerations of RAP, rather than downsize the aggregate gradation. Compression-type crushers such as jaws and cones can clog due to packing (caking) of RAP when the RAP is warm or wet.
Contaminants such as soil are part of processing demolition concrete. Mobile impact and jaw crushers when possessing integrated, independent prescreens removing dirt and fines before they ever enter the crushing circuit reduce equipment wear, save fuel, and with some customers, create a salable fill byproduct. A lined, heavy-duty vibrating feeder below the crusher can eliminate belt wear from rebar or dowel or tie bar damage. If present beneath the crusher, this deflector plate can keep tramp metal from degrading the conveyor belt. That way, the feeder below the crusher not the belt absorbs impact of rebar dropping through the crusher.
These mobile jaw and impact crushers may feature a diesel and electric-drive option. In this configuration, the crusher is directly diesel-driven, with the conveyor troughs, belts and prescreen electric-driven via power from the diesel generator. This concept not only reduces diesel fuel consumption, but also results in significantly reduced exhaust emissions and noise levels. This permits extremely efficient operation with low fuel consumption, allowing optimal loading of the crusher.
Jaw crushers operate according to the principle of pressure crushing. The raw feed is crushed in the wedge-shaped pit created between the fixed crusher jaw, and the crusher jaw articulated on an eccentric shaft. The feed material is crushed by the elliptic course of movement and transported downwards. This occurs until the material is smaller than the set crushing size.
Jaw crushers can be used in a wide range of applications. In the weight class up to 77 tons (70 metric tons), they can be used for both virgin stone and recycled concrete and asphalt aggregates processing as a classic primary crusher for natural stone with an active double-deck grizzly, or as a recycling crusher with vibrating discharge chute and the crusher outlet and magnetic separator.
Output for mobile jaw crushers ranges from 100 to 1,500 tph depending on the model size and consistency of the feed material. While larger mobile crushers produce more aggregate faster, transport weights and dimensions may limit how easily the crusher can be shipped long distances. Mobile jaw crushers can have either a vibratory feeder with integrated grizzly, or a vibrating feeder with an independent, double-deck, heavy-duty prescreen. Either way, wear in the system is reduced because medium and smaller gradations bypass the crusher, with an increase in end-product quality because a side-discharge conveyor removes fines. A bypass flap may provide easy diversion of the material flow, eliminating the need for a blind deck.
Jaw crusher units with extra-long, articulated crusher jaws prevent coarse material from blocking while moving all mounting elements of the crusher jaw from the wear area. A more even material flow may be affected if the transfer from the prescreen or the feeder trough is designed so material simply tilts into the crushing jaw.
Mobile jaw and impact crushers alike can be controlled by one operator using a handheld remote. The remote also can be used to move or relocate the crusher within a plant. In other words, the crusher can be run by one worker in the cab of an excavator or loader as he feeds material into the crusher. If he sees something deleterious going into the hopper, he can stop the crusher.
Impact crushing is totally different from pressure crushing. In impact crushing, feed material is picked up by a fast moving rotor, greatly accelerated and smashed against an impact plate (impact toggle). From there, it falls back within range of the rotor. The crushed material is broken again and again until it can pass through the gap between the rotor and impact toggle.
A correctly configured mobile jaw or impact crusher will enhance material flow through the plant and optimize productivity. New-design mobile jaw and impact crushers incorporate a highly efficient flow concept, which eliminates all restriction to the flow of the material throughout the entire plant. With this continuous-feed system, each step the material goes through in the plant is wider than the width of the one before it, eliminating choke or wear points.
For example, a grizzly feeder can be wider than the hopper, and the crusher inlet wider than the feeder. The discharge chute under the crusher is 4 inches wider than the inner width of the crusher, and the subsequent discharge belt is another 4 inches wider than the discharge chute. This configuration permits rapid flow of crushed material through the crusher. Also, performance can be significantly increased if the conveying frequencies of the feeder trough and the prescreen are adapted independently to the level of the crusher, permitting a more equal loading of the crushing area. This flow concept keeps a choke feed to the crusher, eliminating stops/starts of the feed system, which improves production, material shape and wear.
Users are focused on cost, the environment, availability, versatility and, above all, the quality of the end product. Simple crushing is a relatively easy process. But crushing material so that the particle size, distribution and cleanliness meet the high standards for concrete and asphalt requires effective primary screening, intelligent control for optimal loading, an adjustable crusher with high drive output, and a screening unit with oversize return feed.
This starts with continuous flow of material to the crusher through a variable-speed control feeder. Having hopper walls that hydraulically fold integrated into the chassis makes for quick erection of hopper sides on mobile units. If available, a fully independent prescreen for either jaw or impact models offers the ability to effectively prescreen material prior to crushing this allows for product to be sized prior to crushing, as opposed to using a conventional vibrating grizzly. This has the added value of increasing production, reducing wear costs and decreasing fuel consumption.
This independent double-deck vibrating screen affects primary screening of fines and contaminated material via a top-deck interchangeable punched sheet or grizzly, bottom-deck wire mesh or rubber blank. Discharged material might be conveyed either to the left or to the right for ease of positioning. The independent double-deck vibrating prescreen improves flow of material to the crusher, reducing blockages and feed surges.
Modern electrical systems will include effective guards against dust and moisture through double-protective housings, vibration isolation and an overpressure system in which higher air pressure in the electrical box keeps dust out. Simple and logical control of all functions via touch panel, simple error diagnostics by text indicator and remote maintenance system all are things to look for. For crushing demolition concrete, look for a high-performance electro- or permanent magnet with maximum discharge capacity, and hydraulic lifting and lowering function by means of radio remote control.
For impact crushers, a fully hydraulic crusher gap setting with automatic zero-point calculation can speed daily set-up. Featured only on certain mobile impact crushers, a fully hydraulic adjustment capability of the crushing gap permits greater plant uptime, while improving quality of end product.
Not only can the crushing gap be completely adjusted via the touch panel electronic control unit, but the zero point can be calculated while the rotor is running. This ability to accurately set the crusher aprons from the control panel with automatic detection of zero-point and target-value setting saves time, and improves the overall efficiency and handling of the crusher. On these mobile impact crushers, the zero point is the distance between the ledges of the rotor and the impact plates of the lower impact toggle, plus a defined safety distance. The desired crushing gap is approached from this zero point.
While the upper impact toggle is adjusted via simple hydraulic cylinders, the lower impact toggle has a hydraulic crushing gap adjustment device, which is secured electronically and mechanically against collision with the rotor. The crushing gap is set via the touch screen and approached hydraulically. Prior to setting of the crushing gap, the zero point is determined automatically.
For automatic zero-point determination with the rotor running, the impact toggle moves slowly onto the rotor ledges until it makes contact, which is detected by a sensor. The impact toggle then retracts to the defined safe distance. During this procedure, a stop ring slides on the piston rod. When the zero point is reached, the locking chamber is locked hydraulically and the stop ring is thus fixed in position. The stop ring now serves as a mechanical detent for the piston rod. During the stop ring check, which is carried out for every crusher restart, the saved zero point is compared to the actual value via the electronic limit switch. If the value deviates, a zero-point determination is carried out once again.
These impact crushers may feature a new inlet geometry that allows even better penetration of the material into the range of the rotor. Also, the wear behavior of the new C-form impact ledges has been improved to such an extent that the edges remain sharper longer, leading to improved material shape.
The machines come equipped with an efficient direct drive that improves performance. A latest-generation diesel engine transmits its power almost loss-free directly to the crushers flywheel, via a fluid coupling and V-belts. This drive concept enables versatility, as the rotor speed can be adjusted in four stages to suit different processing applications.
Secondary impact crushers and cone crushers are used to further process primary-crushed aggregate, and can be operated with or without attached screening units. These crushers can be used as either secondary or tertiary crushers depending on the application. When interlinked to other mobile units such as a primary or screen, complicated technical processing can be achieved.
Mobile cone crushers have been on the market for many years. These machines can be specially designed for secondary and tertiary crushing in hard-stone applications. They are extraordinarily efficient, diverse in application and very economical to use. To meet the diverse requirements in processing technology, mobile cone crushing plants are available in different sizes and configurations. Whether its a solo cone crusher, one used in addition to a triple-deck screen for closed-loop operation, or various-size cone crushers with a double-deck screen and oversize return conveyor, a suitable plant will be available for almost every task.
Mobile cone crushers may be available with or without integrated screen units. With the latter, an extremely efficient triple-deck screen unit may be used, which allows for closed-loop operation and produces three final products. Here the screen areas must be large so material quantities can be screened efficiently and ensure that the cone crusher always has the correct fill level, which is particularly important for the quality of the end product.
Mobile, tracked crushers and screen plants are advancing into output ranges that were recently only possible using stationary plants. Previously, only stationary plants were used for complicated aggregate processing applications. But thanks to the advancements made in machine technology, it is becoming increasingly possible to employ mobile technology for traditional stationary applications.
Mobile crushers are used in quarries, in mining, on jobsites, and in the recycling industry. These plants are mounted on crawler tracks and can process rock and recycling material, producing mineral aggregate and recycled building materials respectively for the construction industry. A major advantage of mobile crushers is their flexibility to move from one location to the next. They are suitable for transport, but can also cover short distances within the boundaries of their operating site, whether in a quarry or on the jobsite. When operating in quarries, they usually follow the quarry face, processing the stone directly on site.
For transport over long distances to a new location or different quarry, mobile crushers are loaded on low trailers. No more than 20 minutes to an hour is needed for setting the plant up for operation. Their flexibility enables the mobile crushers to process even small quantities of material with economic efficiency.
Mobile plants allow the combination of prescreening that prepares the rock for the crushing process and grading, which precisely separates defined aggregate particle sizes into different end products to be integrated with the crushing unit into one single machine. In the first stage, the material is screened using an active prescreen. After prescreening, it is transferred to the crusher, from where it is either stockpiled via a discharge conveyor or forwarded to a final screen or a secondary crushing stage. Depending on the specified end product, particles are then either graded by screening units or transported to additional crushing stages by secondary or tertiary impact crushers or cone crushers. Further downstream screening units are used for grading the final aggregate fractions.
The process of prescreening, crushing and grading is a common operation in mobile materials processing and can be varied in a number of ways. Mobile crushers with up to three crushing stages are increasingly used in modern quarries. Different mobile crushing and screening plants can be combined for managing more complex crushing and screening jobs that would previously have required a stationary crushing and screening plant.
Interlinked mobile plants incorporate crushers and screens that work in conjunction with each other, and are coordinated in terms of performance and function. Mining permits are under time constraints and mobile plants provide faster setup times. They provide better resale value and reusability, as mobile plants can also be used individually. They also reduce operating costs in terms of fewer haul trucks and less personnel.
With a so-equipped mobile crusher, the feed operator can shut the machine down or change the size of the material, all using the remote control, or use it to walk the crusher from one part of the site to the other, or onto a flat bed trailer for relocation to a different quarry or recycling yard. This reduces personnel and hauling costs compared to a stationary plant. With the mobile jaw or impact primary crusher, the only additional personnel needed would be a skid-steer operator to remove scrap steel, and someone to move the stockpiles.
Thanks to better technology, mobile plants can achieve final aggregate fractions, which previously only were possible with stationary plants. Production availability is on par with stationary plants. Theyre applicable in all quarries, but can be used for small deposits if the owner has several quarries or various operation sites. For example, an operator of several stone quarries can use the plants in changing market situations at different excavation sites. In addition, they also can be used as individual machines. A further factor is that mobile plants, in general, require simpler and shorter licensing procedures.
The high cost of labor keeps going up. A stationary crusher might be able to produce multiple times the amount of product, but also would require about seven or eight workers. Aggregate producers can benefit when producing material with the minimized crew used for mobile jaw and impact crushers.
Using correct maintenance practices, mobile crushers will remain dependable throughout their working life. Crushing and processing material can result in excessive wear on certain components, excessive vibration throughout the plant, and excessive dust in the working environment. Some applications are more aggressive than others. A hard rock application is going to require more maintenance on top of standard maintenance, as there will be more vibration, more dust and more wear than from a softer aggregate.
Due to the nature of its purpose, from the moment a mobile crusher starts, the machine is wearing itself out and breaking itself down. Without routine, regular maintenance and repair, a mobile crusher will not be reliable nor provide the material customers demand.
The first area of wear on any machine is the feed system. Whether its a feeder with an integrated grizzly, or a feeder with an independent prescreen, how the machine is fed contributes to wear. When setting up and maintaining a machine, the machine must be level. A machine that is unlevel left to right will experience increased wear on all components, including the feeder, the screens, the crushing chambers and the conveyor belts. In addition, it reduces production and screening efficiency, as the whole area of the machine is not being effectively used. Also, having the machine sit high at the discharge end will have the effect of feeding the material uphill in the feeder and reducing its efficiency, thus reducing production.
Another area for consideration is the equipment used to feed the machine. The operator using a loader to feed the crusher will have no control over the feed size, as he cannot see whats in the bucket. Whereas with an excavator, the operator can see whats inside and has more control over the feed into the hopper. That is, the operator is not feeding so much material all at once and is controlling the size of the feed. This reduces wear in the feed hoppers impact zones and eliminates material blockages due to feed size being too large to enter the chamber.
Dust is a problem in its own right, especially for the power plant of the mobile crusher. In a very dusty application, it is easy to plug the radiator and have engine-overheating problems. High dust levels cause increased maintenance intervals on air filters, and if not controlled properly, can enter the diesel tank and cause problems with the fuel system. Also, dust that gets inside the crusher increases wear. But if systems are put in place to remove the dust, it should keep it from going into the machine in the first place.
Dust also is a hazard on walkways and a problem for conveyors. If maintained, side-skirting and sealing the conveyors keeps dust from spilling out, building up underneath the conveyor, or building up in rollers, pulleys, bearings, and causing wear on shafts. Its important to maintain the sealing rubbers on the conveyor belts to avoid those issues. Routine maintenance calls for removing accumulated dust from inside and under the machine.
Dust also is a problem for circuit boards and programmable controllers. Dust causes electrical switches to malfunction because it stops the contacts from correctly seating. Electrical systems under positive air pressure dont permit dust to penetrate the control system. In control panels with a correctly maintained positive pressure system, filters remove dust from air that is being pumped into the cabinets. If the filters are plugged, the system will not pull as much air through, allowing dust, moisture and heat to build in the cabinet.
There are also impact aprons against which the rock is thrown, which also see high wear. There are side plates or wear sheets on the sides of the machine. The highest wear area is around the impact crusher itself, around the circumference of the rotor. If not maintained, the wear items will wear through and compromise the structure of the crusher box.
Conduct a daily visual check of the machine. The jaw is simple; just stand up on the walkway and take a look down inside. A crushers jaw plate can be flipped so there are two sides of wear on them. Once half the jaw is worn out, flip it; once that side is worn, change it.
The impact crusher will have an inspection hatch to see inside. Check to see how much material is left on the blow bars and how much is left on the wear sheets on the side of the crusher box. If half the bar is worn out after one week, change the blow bars in another week.The frequency of changes depends entirely on the application and the rock that is being crushed.
They have to be user serviceable, user friendly, and able to be changed in a short time. The best way to change these parts is a service truck with a crane; some use excavators but thats not recommended by any means.
After initial blasting, breakers are used to break down aggregate that typically is not only too large to be hauled in dump trucks, but also too large for crushers that size rock to meet asphalt, drainage system, concrete and landscaping specifications. Breakers can be mounted to a mobile carrier, such as an excavator, or to stationary boom systems that can be attached to a crusher. The total number of hydraulic breakers can vary from site to site depending on production levels, the type of aggregate materials and the entire scope of the operation.
Without hydraulic breakers, workers rely on alternative practices that can quickly affect production rates. For instance, blasting mandates shutting down operations and moving workers to a safe location. And when you consider how many times oversize aggregate might need to be reduced, this can lead to a significant amount of downtime and substantially lower production rates.
Aggregate operations can use hydraulic breakers to attack oversize without having to clear the quarry. But with an ever-growing variety of manufacturers, sizes and models to choose from, narrowing the decision to one hydraulic breaker can be overwhelming with all of the stats and speculation. Thats why its important to know what factors to consider before investing in a new hydraulic breaker.
In most cases, heavy equipment dealers are very knowledgeable about quarry equipment, including breakers, so they are a good resource for finding the best model for a carrier, usually an excavator or stationary boom system. More than likely, they will have specifications and information about various breaker sizes to help gauge what model is best. But being familiar with what to look for in a breaker can streamline the selection process.
The best places to look for breaker information are in the manufacturers brochure, website, owners manual or catalogue. First, carefully review the carrier weight ranges. A breaker that is too big for the carrier can create unsafe working conditions and cause excessive wear to the carrier. An oversized breaker also transmits energy in two directions, toward the aggregate and through the equipment. This produces wasted energy and can damage the carrier. But using a breaker thats too small puts excessive force on the tool steel, which transmits percussive energy from the breaker to the material. Using breakers that are too small also can damage mounting adapters and internal components, which considerably decreases their life.
Once you find a breaker that meets the carriers capacity, check its output power, which is typically measured in foot-pounds. Foot-pound classes are generalizations and are not based on any physical test. Often the breakers output will be documented in one of two ways: as the manufacturers calculated foot-pound class or as an Association of Equipment Manufacturers measured foot-pound rating. Foot-pound class ratings can be deceiving since they are loosely based on the breakers service weight and not the result of any physical test. The AEM rating, on the other hand, measures the force a breaker exerts in a single blow through repeatable and certified testing methods. The AEM rating, which was developed by the Mounted Breaker Manufacturers Bureau, makes it easier to compare breaker models by reviewing true figures collected during an actual test procedure.
For instance, three breaker manufacturers might claim their breakers belong in a 1,000-lb. breaker class. But AEM testing standards could reveal all three actually have less foot-pound impact. You can tell if a breaker has been AEM tested if a manufacturer provides a disclosure statement or if the breaker is labeled with an AEM Tool Energy seal. If you cannot find this information, contact the manufacturer. In addition to output energy specifications, manufacturers often supply estimates for production rates on different types of aggregate material. Make sure to get the right measurements to make the best decision.
In addition to weight and output power, look at the breakers mounting package. Two things are crucial for mounting a breaker to a carrier: a hydraulic installation kit and mounting components. Breakers need hydraulic plumbing with unidirectional flow to move oil from the carrier to the breaker and back again. A one-way flow hydraulic kit is sufficient to power the breaker as long as the components are sized to properly handle the required flows and pressures. But, consider a bidirectional flow hydraulic kit if you plan to use the same carrier with other attachments that require two-way flow. Check with the dealer or breaker manufacturer to determine which hydraulic package best fits current and future needs.
Hydraulic flow and pressure specifications also need to be considered when pairing a breaker to a hydraulic system. If the carrier cannot provide enough flow at the right pressure, the breaker wont perform with maximum output, which lowers productivity and can damage the breaker. Additionally, a breaker receiving too much flow can wear quickly, which reduces its service life. For the best results, follow the hydraulic breaker specifications found in owners manuals, catalogs and brochures. Youll find out if a breaker has additional systems that might require additional servicing. For instance, some breakers feature nitrogen gas-assist systems that work with the hydraulic oil to accelerate the breakers piston. The nitrogen systems specifications need to be followed for consistent breaker power output.
Brackets or pin and bushing kits are commonly required to attach the breaker to the carrier. Typically they are bolted to the top of a breaker and are configured to match a specific carrier. Some manufacturers make universal mounting brackets that can accommodate two or three different sizes of carriers. With the adjustable pins, bushings or other components inside these universal brackets, the breaker can fit a range of carriers. However, varying distances between pin centers can complicate hookups to quick coupling systems. In addition, loose components, such as spacers, can become lost when the breaker is not in use and detached from the carrier.
Some carriers are equipped with quick-coupling systems, which require a breakers mounting interface to be configured like the carriers original attachment. Some manufacturers produce top-mount brackets that pair extremely well with couplers. This allows an operator to use the original bucket pins from the carrier to attach the breaker, and eliminates the need for new pins. This pairing also ensures a fast pickup with the quick coupler.
Its also a good idea to check which breaker tools are available through the dealer and manufacturer. The most common for aggregate mining are chisels and blunts. There are two kinds of chisels commonly used in aggregate mines: crosscut and inline. Both chisels resemble a flat head screwdriver, but the crosscut chisels are used when carrier operators want to direct force in a left-to-right concentration; whereas, inline chisels direct force fore and aft. With chisel tools, operators can concentrate a breakers energy to develop cracks, break open seams or define scribe lines.
If a chisel cant access or develop a crack or seam, a blunt can be used. Blunts have a flattened head that spreads the energy equally in all directions. This creates a shattering effect that promotes cracks and seam separation. Ask your dealer if the tools you are considering are suited for the application. Using non-original equipment manufacturer tool steel can damage the percussive piston in the breaker, seize into the wear bushings, or cause excessive wear.
Regular breaker maintenance is necessary, yet its one of the biggest challenges for aggregate operations. It not only extends the life of the breaker, but also can keep minor inconveniences from turning into expensive problems. Some manufacturers recommend operators inspect breakers daily to check grease levels and make sure there are no worn or damaged parts or hydraulic leaks.
Breakers need to be lubricated with adequate amounts of grease to keep the tool bushing area clear and reduce friction, but follow the manufacturers recommendations. For example, adding grease before properly positioning the breaker can lead to seal damage or even catastrophic failure. And too little grease could cause the bushings to overheat, seize and damage tools. Also, manufacturers advise using high-moly grease that withstands working temperatures greater than 500 degrees. Some breakers have automatic lube systems that manage grease levels, but those systems still need inspections to ensure there is adequate grease in their vessels. Shiny marks on the tool are a good indication the breaker is not properly lubricated.
Little has changed in basic crusher design over past decades, other than that of improvements in speed and chamber design. Rebuilding and keeping the same crusher in operation year after year has long been the typical approach. However, recent developments have brought about the advent of new hydraulic systems in modern crusher designs innovations stimulated by the need for greater productivity as well as a safer working environment. Importantly, the hydraulic systems in modern crusher designs are engineered to deliver greater plant uptime and eliminate the safety risks associated with manual intervention.
Indeed the crushing arena is a hazardous environment. Large material and debris can jam inside the crusher, damaging components and causing costly downtime. Importantly, manually digging out the crusher before repairs or restarts puts workers in extremely dangerous positions.
The Mine Safety and Health Administration has reported numerous injuries and fatalities incurred when climbing in or under the jaw to manually clear, repair or adjust the typical older-style jaw crusher. Consider that fatalities and injuries can occur even when the machine is locked out and tagged out. Recent examples include a foreman injured while attempting to dislodge a piece of steel caught in the primary jaw crusher. Another incident involved a fatality when a maintenance man was removing the toggle plate seat from the pitman on a jaw crusher. The worker was standing on a temporary platform when the bolts holding the toggle seat were removed, causing the pitman to move and strike him.
The hydraulic systems on modern crusher designs eliminate the need for workers to place themselves in or under the crusher. An overview of hydraulic system technology points to these three key elements:
A hydraulic chamber-clearing system that automatically opens the crusher to a safe position, allowing materials to pass. A hydraulic overload relief that protects parts and components against overload damage. A hydraulic adjustment that eliminates the maintenance downtime associated with manual crusher adjustments, and maintains safe, consistent crusher output without the need for worker intervention.
Whether a crusher is jammed by large material, tramp iron or uncrushable debris; or is stalled by a power failure the chamber must be cleared before restarting. Manual clearing is a lengthy and risky task, especially since material can be wedged inside the crusher with tremendous pressure, and dislodging poses much danger to workers placed in harms way inside the crusher.
Unlike that of the older-style jaw, the modern jaw will clear itself automatically with hydraulics that open the crusher to a safe position, and allow materials to pass again, without the need for manual intervention. If a feeder or deflector plate is installed under the crusher, uncrushable material will transfer smoothly onto the conveyor without slicing the belt.
To prevent crusher damage, downtime and difficult maintenance procedures, the hydraulic overload relief system opens the crusher when internal forces become too high, protecting the unit against costly component failure. After relief, the system automatically returns the crusher to the previous setting for continued crushing.
The modern crusher is engineered with oversized hydraulic cylinders and a traveling toggle beam to achieve reliable overload protection and simple crusher adjustment. All closed-side setting adjustments are made with push-button controls, with no shims being needed at any time (to shim is the act of inserting a timber or other materials under equipment). This is a key development as many accidents and injuries have occurred during shim adjustment, a process which has no less than 15 steps as described in the primary crusher shim adjustment training program offered by MSHA.
Product Introduction JXSC jaw type rock crusher is usually used as a primary crusher and secondary crusher to reduce the size of medium-hard materials to smaller physical size. Jaw rock crushers are capable of working with the mobile crushing station, underground crushing because of its related small volume. Capacity: 1-1120TPH Max Feeding Size: 120-1200mm Application Mining, metallurgy, building materials, quarrying, gravel & sand making, aggregate processing, recycling, road and railway construction and chemical industry, etc. Suitable Material Granite, marble,basalt, limestone, coal, quartz, pebble, iron ore, copper ore, etc.
40 years of manufacturing and engineering experience keep us innovative and knowledge in the rock break machines and its applications, which thus provide reliable industry rocks crushers and solutions for every customer using jaw crusher manufacturers JXSC machines to meet their production goals. The jaw crusher machine family consists of different sized models that are designed to bring maximum output with minimum cost. Some workplaces have limited conditions and are unable to provide electricity or are underpowered. According to these conditions, JXSC specially designed diesel jaw crusher. The diesel-jaw crusher is actually with electric, but the original jaw crusher was added with a diesel engine equipment that a dual-purpose crusher.
JXSC the crushers machine with a non-welded frame has been proved that it has outstanding solid and durable strength. All the alloy casting frame components turn out that with premium quality, wear-resistant property.
The design of pitman and long stoke improves productivity and reduction. A wider feeding material opening increases the volume of insulating material and makes the ore material entering the crushers crushing chamber smoothly. A sharp angle makes the materials flow down speed faster and reduces the wear cost. Besides, the strike force could be stronger thus increase the production efficiency as well as the reduction ratio.
Types of jaw crushers: on the basis of the stone break equipment size and capacity can divide into a heavy and small(mini) portable jaw rock crushers. According to the working principle can be split into single toggle and double toggle jaw rock crushers machine.
A series of jaw stone crushers use compressive and squeezing force for reducing materials. This physical force is created by the two jaw plates, one of which is a movable plate and another is fixed, both of them are made of manganese. A V-shaped cavity, crushing chamber, is formed and the hydraulic discharge gap width of the crushing chamber, we can determine the suited feeding material size and discharging size, the width of top feeding is larger than that of bottom discharging.
Jaw crusher is a heavy-duty machine that crushes hard materials. So its hence muse be robustly constructed. Crusher frame is made from steel or cast iron. The jaws are made of cast steel. The liners are made fromNi-hard, Ni-Cr alloyed cast iron or manganese steel which can replaceable and use to reduce frame wear. The cheek plates are also made from hard alloy steel and installed to the sides of the crushing chamber to protect the frame from wear.
The jaws can be made in smooth or corrugated, but often corrugated. Because the latter crushing the hard and abrasive ores is better. The angle between the jaws is usually less than 26. This is because a large angle will cause the particle to slip which non-crush.
It uses curved plates to avoid the near the discharge of jaw crusher blocking. The bottom of the swinging jaw is concave, and the relative lower part of the fixed jaw is convex. The materials reduction in size when nears the exit. So the material is distributed over a larger area, and the jaws plates wear less.
The type of crushed materials determines how to design the max amplitude of swing of the jaw and the amplitude adjusted by changing the eccentric. The length from 1 to 7 cm depends on the crusher machine size. Jaw crushers are supplied in sizes up to 1,600 mm (gape)1,900 mm (width). For coarse crushing application (closed set~300 mm), capacities range up to 1200 tph.
Jaw crusher parts must have some wear after a period of use, but the easily damaged parts will wear out more. The price of crushing equipment with the same specifications and handling capacity is different in the material of parts.
Guard Plate The guard plate is made of high-quality high manganese steel, which is located between the fixed plate and the movable plate. The whole body is mainly to protect the jaw crusher frame wall.
Toothed Plate Tooth plate is divided into movable and fixed tooth plate, but both is made from high manganese steel casting. In order to prolong its service life, its shape is designed to be symmetrical. That is when one end of the wear can be used to turn the head. The movable and the fixed teeth plate are the main parts for stone crushing. So the movable teeth plate is installed on the movable jaw to protect the movable jaw.
Toggle Plate The toggle plate is a cast iron piece that has been precisely calculated. It is not only a force transmission component but also the safety parts of the crusher. When the crusher falls into the non-crushing material and makes the machine beyond the normal load, the toggle plate will immediately break. Then the crusher machine stops operation, thus avoiding the damage of the whole machine. The toggle plate and the toggle plate spacer adopt the rolling contact model which less attrition under normal use. It just needs smear a layer of grease on the contact surface is ok.
Triangular Belt When the motor transmits power, the triangle belt is connected with the pulley and the grooved pulley of the motor to drive the eccentric shaft and make the moving jaw move back and forth according to the predetermined track.
The tooth plate of the most jaw crushers are made of manganese steel, bearing linings are made of babbitt alloy, sliding blocks are made of carbon steel, toggle plates are made of cast iron, springs are made of 60SiMn. Regular Inspection and maintenance of the machine can extend its service life. In order to reduce customer costs, we will generally be in the purchase of customers are advised to buy some spare parts. Because once the parts need to be replaced, the temporary purchase will take some time. The wait time may cause the entire breakage line to suspend operations, thereby increasing operating costs.
In short, the jaw stone crushers are mainly used for primary crusher, the crushing stone is relatively large. The types of crusher machine's chamber are deep and no dead zone. It improves that the feeding capacity and output. The crushing ratio is large and the product particle size is even. Shim type outlet adjustment device, reliable and convenient, large hydraulic adjustment range that increased the flexibility of the equipment. Simple structure, reliable work and low operation cost. The adjustment range of hydraulic discharge opening is large, which can meet the requirements of different users, low noise and less dust.
Impact crusher for crushing medium-hard stones, and mostly used for secondary crusher. The impact crushers have a big feeding port, high crushing cavity, high material hardness, big block size and little stone powder. Convenient maintenance, economic and reliable, high comprehensive benefit.
Jiangxi Shicheng stone crusher manufacturer is a new and high-tech factory specialized in R&D and manufacturing crushing lines, beneficial equipment,sand-making machinery and grinding plants. Read More
Efficiency can be defined by the ratio of work done by a machine to the energy supplied to it. To apply what this means to your crusher, in your reduction process you are producing exactly the sizes your market is demanding.
In the past, quarries produced a range of single-size aggregate products up to 40mm in size. However, the trend for highly specified aggregate has meant products have become increasingly finer. Currently, many quarries do not produce significant quantities of aggregate coarser than 20mm; it is not unusual for material coarser than 10mm to be stockpiled for further crushing.
A jaw crusher is a compression-type of crusher. Material is reduced by squeezing the feed material between a moving piece of steel and a stationary piece. The setting or the space between those two pieces of steel controls the discharge size. The tighter the setting, the smaller the output size and the lower the throughput capacity. Jaw crushers are mainly used in primary crushing; they are rarely used as a secondary crusher.
As compression crusher, jaws generally produce the coarsest material because they break the rock by the natural inherent lines of weakness. A jaw crusher can be an excellent primary crusher when used to prepare rock for subsequent processing stages such as washing, classifying or a secondary crusher.
Try to choke-feed any compression-type crusher. Remember, we are using gravity and the weight of the material to push or force material through the chamber. Since in a compression machine the material breaks to fill the air pockets or voids in the chamber, a non-choke chamber will produce a slabbier output than a choke-fed chamber.
Jaw crushers are routinely choke-fed, as this maximises production capacity and ensures particles are uniformly broken. This promotes stone-on-stone crushing, which breaks up flaky or slabbier particles. If you are seeking fewer fines, trickle-feeding material into the jaw crusher could achieve this; however, this would have an adverse effect on particle shape and would also reduce throughput capacity, hindering the crushers efficiency.
Ideally, the feed rate should not be switched from choke to non-choke, as this would cause problems downstream at the secondary processing plant. In practice, many jaw crushers are fed in this intermittent fashion due to gaps in the delivery of feed material from the quarry. Jaw crusher feed should be pre-screened using a grizzly screen prior to crushing, to remove material finer than the closed side setting (CSS).
In practice, many jaw crushers are not fed to their design capacity; this is because the subsequent processing plant does not have sufficient capacity to handle the volume of material that would be produced if the jaw crusher were working to capacity.
Ideally, the reduction ratio of a jaw crusher should be 6:1. There are different ways to calculate reduction ratio, but the best way is something called the P80 factor. The reduction ratio is then calculated by comparing the input feed size passing 80 per cent versus the discharge size that passes 80 per cent. The finer the CSS, the greater the proportion of fines produced. The CSS of a jaw crusher helps determine the nip angle within a chamber, typically 19 to 23 degrees. Too large an angle causes boiling in the crushing chamber; this is where the jaw plates cannot grip onto the rock and it keeps slipping up and down, avoiding being crushed. The nip angle gets flatter as the machine is set tighter.
The settings on a jaw crusher are designed to produce material ideal for secondary crushing. The best particle shape is typically found in material about the same size as the CSS. Smaller sizes will contain a higher proportion of elongated particles because they have passed through the crusher without being touched. Larger sizes may also contain a higher proportion of elongated particles, as they are further from the CSS, which can cause bridging issues in downstream machines. The bottom line is that the best particle shape and performance comes from a choke-fed chamber.
Cone crushers and gyratory crushers are also compression-type machines that crush material between moving and stationary pieces of steel. The setting between the two pieces of steel controls the output. Though the chamber is round in shape, the moving piece of steel is not meant to rotate. Instead a wedge is driven around to create compression on one side of the chamber and discharge opening on the opposite side.
Cone crushers are used in secondary and tertiary roles as an alternative to impact crushers, when shape is an important requirement but the proportion of fines produced needs to be minimised. Even though the reduction in fines produced may be only a few percentage points, this could represent a significant amount of material in a large operation and, ultimately, increase an operations bottom line and profitability.
Increasing the CSS in an attempt to reduce the amount of fines produced may have the opposite effect; it may lead to a greater proportion of oversized material, which would need re-crushing in the remaining crushing circuits and would ultimately lead to a higher proportion of fines being produced. The further in the crushing process, the greater the amount of fines produced.
It is critical that a cone-type crusher be choke-fed to produce the best product shape and quality. It is not as important in a jaw, as material is not generally stockpiled after the jaw. Since the cone is in the secondary and tertiary stations, particle shape assisted by a choke-fed chamber is important, as it creates finished products in these stages.
Uniform distribution of feed material around the cone crusher inlet is a good practice. This allows production of a consistent product, as well as efficient, reliable operation of the crusher. Choke-feeding is important for cone crushers because it maintains a good particle shape by facilitating an inter-particle crushing action. Trickle feeding is not the best option because it increases the proportion of flaky material in the crusher product, hindering its efficiency.
It is a good rule to maintain about 10 to 15 per cent of material finer than the CSS in the feed to assist crushing action. More than 10 to 15 per cent will likely cause ring bounce due to the pressures in the chamber.
Pre-screening of the feed to remove the fines, especially in tertiary crushing, is a good practice; it helps to avoid packing of material in the chamber while maintaining an efficient, effective crushing action and increasing your crusher efficiency.
The liner profiles are designed for a range of product sizes, from extra coarse (EC) to extra fine (EF). The EF liner profile will result in the highest fines proportion for a given cone crusher. It is important to find the right liner for the feed gradation and desired product. If the liner is too large, feed material will drop too far in the chamber before being crushed. Too fine a liner will prevent material from entering the chamber at all.
Monitoring the crushing force as registered through the load on the crusher motors, as well as the pressure on the hydraulic mantle adjustment mechanism, will give forewarning of crusher packing problems before they affect your efficiency.
The finer the CSS, the greater the proportion of fines produced. The finer setting also lowers throughput volume. It is important to match the CSS of the crusher to the top size of the product to be produced. If the circuit is being closed at 25mm (1) to produce a 25mm minus product, the crusher should be set at, near or slightly below 25mm.
An impact crusher uses mass and velocity to break down feed material. First, the feed material is reduced as it enters the crusher with the rotating blow bars or hammers in the rotor. The secondary breakage occurs as the material is accelerated into the stationary aprons or breaker plates. Impact crushers tend to be used where shape is a critical requirement and the feed material is not very abrasive. The crushing action of an impact crusher breaks a rock along natural cleavage planes, giving rise to better product quality in terms of shape. The quality of these products makes them ideal for use in highly specified road, stone and concrete aggregate applications.
Establishing the proper rotational speed of the blow bars or hammers is critical for efficient reduction and production. Also, the angle of the feed plate that introduces the feed material to the rotor assists in the efficiency of the machine. Improper rotor penetration will result in decreased performance.
Size reduction in an impact crusher relies on energy being conveyed into the rock from the rotor, and it begins with your feed. The initial impact is responsible for more than 60 per cent of the crushing action, with the remainder made up of impact against an adjustable breaker bar and a small amount of inter-particle collision. This is why it is vitally important that the feed arrangement to an impact crusher ensures an even distribution of feed material across the full width of the rotor. This will allow for even distribution of energy into the feed material and uniform wear patterns, ensuring consistent product gradation and power consumption.
Establishing the proper rotational speed of the blow bars or hammers is critical for efficient reduction and production. Also, the angle of the feed plate that introduces feed material to the rotor assists in the efficiency of the machine. Improper rotor penetration will result in decreased performance.
Size reduction and, ultimately, the crusher setting are directly proportional to the rotor speed; it largely dictates how many fines are produced. Slower rotor speeds can be used as a means of reducing fines, but may result in a product with more oversize or return than is wanted. Slower rotor speeds are preferable as a means of minimising the wear on crusher components and for achieving less fines production and optimal product size.
The product grading from an impact crusher will change throughout the life of the wear parts, particularly the impact hammers or blowbars. As the profile of the hammer changes with increased wear, the product grading becomes coarser. Many modern impact crusher installations have a variable speed drive arrangement that allows an increase in the rotor speed to compensate for wear on the impact hammers.
In many impact crushers, a third curtain or crushing chamber can be added to increase reduction in every pass through the machine. This can be important in finer product applications, where the third chamber can provide the desired output gradation. A third chamber that increases the reduction will also increase the power needs and, normally, the wear cost.
Decreasing the gap between the hammers and impact curtain increases particle retention in the chamber. This increases the size reduction ratio; however, it also reduces efficiency throughput capacity and increases fines production.
Crushing efficiency begins with common crusher knowledge. Once you have a machine a jaw, cone/gyratory or impact crusher how you feed it and how you set it will affect its efficiency. By taking many of the steps outlined above to achieve the best crushing outcome, producers can reduce the amount of fines they produce and save more dollars for their pockets.
Save to read list Published by John Williams, Editorial Assistant Dry Bulk, Friday, 05 June 2020 12:18
According to the Health and Safety Executives guidance for the safe operation and use of mobile jaw crushers, equipment operators may be subject to multiple risks including exposure to dust, noise, whole body vibration and being struck by objects ejected from the crusher. Here is how, WEGs main distributor, Technidrive, developed an energy efficient automatic jaw crusher unblock system using entirely WEG products.
Commonly used in the quarrying, mining, recycling of demolition waste and chemical industries, jaw crushers are a reasonably difficult application for systems integrators, due to the large inertia of the fly wheel, cyclic loading and differences in materials that customers feed them with.
This did not prove to be a problem for Technidrive, who were initially approached by a customer looking to implement a new motor in their jaw crusher machine. With over 20 years experience in industrial drives, Technidrive used its expertise to meet the demands of the project and exceed the initial requirements. Using a combination of quality WEG products, Technidrive was not only able to improve the efficiency and reliability of the motor, but the efficiency and safety of the entire jaw crusher system. WEG was asked to supply the motor, control and alternator for the project due to the quality, versatility and energy efficiency of its product line and its technical expertise.
Crushing is an important process in turning rock into a useable product. Rock enters the jaw crusher from the top of the machine and gets compressed between two surfaces the fixed and moveable jaw. The rock will continue to be crushed until it is small enough to fall through the opening. Ensuring that the size of raw material is appropriately matched to the jaw opening, can alleviate blockage incidents. This can be achieved by removing oversize product prior to processing and careful control of the crusher feeder, however blockages do still occur. To unblock a crusher a plant must be shut down and the system must first be isolated, but despite these precautions a crusher can still be a serious risk to personnel, due to the amount of kinetic energy that is released during unblocking.
Technidrive commenced this project by carrying out power torque and speed calculations to decide upon a suitable selection of WEG electric motor and gear units. The electric motor was selected based on the power and speed and further mechanical calculations were carried out to ensure the motor shaft could cater for the high radial loads the application can impose. The WEG W22 motor was eventually selected for its superior cast iron frame, inverter rated windings and insulated non-drive end flange.
The next vital part of the system is the control of the motor, which can incorporate a soft start or variable speed drive (VSD) to control the motor starting speed or torque, for example. The VSD model selected was a CFW11 WEG inverter with built in soft programmable logic control (PLC) functions. There were several advantages to this selection, including the standard DC bus chokes to reduce harmonics. The inverter was selected with an output sinusoidal filter to create a nice sine wave, reduce output current and importantly reduce electrical noise.
Electrical disturbances however are not the only consideration, crusher blockages can be a real problem for operators, resulting in periods of prolonged downtime. One of the main advantages of this project was the level of control that was achieved through an innovative piece of software, which Technidrive developed.
On a normal start from empty, the VSD ramps the crusher up on a slow ramp time, restricting the absorbed current due to the high inertia of the application. This not only keeps the power supply requirements low, for a more efficient system, but also reduces the stress on the mechanical system. Over time this can lead to significant maintenance cost savings and extend the life of the machine. It is estimated that a 10C reduction in operating temperature typically doubles the motors lifetime.
The innovative software allowed for a special start up function when starting the jaw crusher from full. In the event that the crusher is stopped full, the VSD is able to be remotely activated in an unblock mode, with a very fast ramp time in forward or reverse depending on the position of the crusher. It will continue to automatically control the direction, current, ramp times, DC bus voltage, torque, position, and speed until the product in the chamber has been cleared and the crusher has run empty for a set period of time. This innovative system removes the dangerous and laborious job operators have had to do for years, by manually unblocking jaw crushers using rock breakers or winches to remove product.
Another very important part of the system was the alternator, which is vital to achieving an efficient and reliable system. According to the International Energy Agency (IEA), 16 per cent of motor failures are due to external conditions, such as contamination, so ensuring application suitability was essential. The alternator selected was from the WEG G-line range with some special features such as a dust filtering system, to allow it to operate in a dusty quarry atmosphere, without the risk of foreign particles entering the system. The alternator also included a digital input AVR to allow remote voltage adjustment, standard I-PMG auxiliary winding system feature to allow a dynamic response to load change and short envelope compared to traditional external PMG alternators.
The complete drive system was expertly selected to work in harmony to address many issues manufactures in the industry come across, explained David Strain, technical director at Technidrive. The added unblocking feature transforms the starting of the application, an often energy intensive process and provides a unique benefit for system safety. With the system supplied, we are able to provide a three-year warranty for the motor and inverter and ensure the three main parts to the drive system all work together for optimum performance and reliability. Since our first jaw crusher project, we have had much interest from other businesses in the quarrying industry. We treat each project on an individual basis, to offer bespoke turnkey systems.
WEG offers specialist products that are developed specifically for the rock crushing industry, explained Russell Maccabe UK Sales Manager at WEG. Its vital that manufacturers and suppliers both have extensive product, application and systems integration knowledge and thats why this project with Technidrive proved to be so successful.
All rock crushers can be classified as falling into two main groups. Compressive crushers that press the material until it breaks, and impact crushers using the principle of quick impacts to crush the material. Jaw crushers, gyratory crushers, and cone operate according to the compression principle. Impact crushers, in turn, utilize the impact principle.
As the name suggest, jaw crushers reduce rock and other materials between a fixed and a moving jaw. The moving jaw is mounted on a pitman that has a reciprocating motion, and the fixed jaw stays put. When the material runs between the two jaws, the jaws compress larger boulders into smaller pieces.
There are two basic types of jaw crushers: single toggle and double toggle. In the single toggle jaw crusher, an eccentric shaft is on the top of the crusher. Shaft rotation causes, along with the toggle plate, a compressive action.
The chewing movement, which causes compression at both material intake and discharge, gives the single toggle jaw better capacity, compared to a double toggle jaw of similar size. Metsos jaw crushers are all single toggle.
Gyratory crushers have an oscillating shaft. The material is reduced in a crushing cavity, between an external fixed element (bowl liner) and an internal moving element (mantle) mounted on the oscillating shaft assembly.
The fragmentation of the material results from the continuous compression that takes place between the liners around the chamber. An additional crushing effect occurs between the compressed particles, resulting in less wear of the liners.
Cone crushers resemble gyratory crushers from technological standpoint, but unlike gyratory crushers, cone crushers are popular in secondary, tertiary, and quaternary crushing stages. Sometimes, however, the grain size of the processed material is small enough by nature and the traditional primary crushing stage is not needed. In these cases, also cone crushers can carry out the first stage of the crushing process.
Cone crushers have an oscillating shaft, and the material is crushed in a crushing cavity, between an external fixed element (bowl liner) and an internal moving element (mantle) mounted on the oscillating shaft assembly.
An eccentric shaft rotated by a gear and pinion produces the oscillating movement of the main shaft. The eccentricity causes the cone head to oscillate between open side setting and closed side setting discharge opening.
The fragmentation of the material results from the continuous compression that takes place between the liners around the chamber. An additional crushing effect occurs between the compressed particles, resulting in less wear of the liners. This is called interparticular crushing also.
Depending on cone crusher, setting can be adjusted in two ways. The first way is for setting adjustment to be done by rotating the bowl against the threads so that the vertical position of the outer wear part (concave) is changed. One advantage of this adjustment type is that liners wear more evenly.
To optimize operating costs and improve the product shape it is recommended that cone crushers are always be choke fed, meaning that the cavity should be as full of rock material as possible. This can be easily achieved by using a stockpile or a silo to regulate the inevitable fluctuation of feed material flow. Level monitoring devices detect the maximum and minimum levels of the material, starting and stopping the feed of material to the crusher, as needed.
Impact crushers are traditionally classified to two main types: horizontal shaft impact (HSI) crushers and vertical shaft impact (VSI) crushers. These different types of impact crushers share the crushing principle, impact, to reduce the material to smaller sizes, but features, capacities and optimal applications are far from each other.
Horizontal shaft impact (HSI) crushers are used in primary, secondary or tertiary crushing stage. HSI crushers reduce the feed material by highly intensive impacts originating in the quick rotational movement of hammers or bars fixed to the rotor. The particles produced are then further fragmentated inside the crusher as they collide against crusher chamber and each other, producing a finer, better-shaped product.
VSI crusher can be considered a stone pump that operates like a centrifugal pump. The material is fed through the center of the rotor, where it is accelerated to high speed before being discharged through openings in the rotor periphery. The material is crushed as it hits of the outer body at high speed and due to rocks colliding against each other.
Selecting optimal crushing equipment can be difficult. Luckily there are tools and software available that simplify weighting different options and help in making decisions. The backbone of all these analyzes are careful calculations that take into account the capabilities and constraints of different crushers and operational requirements.
Every crushing site and operation is different, and theoptimal results are normally obtained by combining theoretical conclusions with practical experience of different materials, operational conditions, maintenance needs, and economic aspects of various alternatives.
Below are some key issues listed according to crushing stages in brief. While defining the best technical solution for your requirements, its good to remember that many crushers are available not only as stationary but also asmobileorportableversions in case you prefer to move or transport your crusher at the production site or between sites regularly.
If you are interested in more detailed analyzes tailored just for your crushing operations, please contact Metso experts. We have practical experience of thousands of different crushing applications around the world, and we are happy to help in finding the equipment that best fits your needs.
The main purpose of a primary crusher is to reduce the material to a size that allows its transportation on a conveyor belt. In most crushing installations a jaw crusher takes care of primary crushing. Plants with very high capacities that are common in mining and less popular in aggregates production, normally use a primary gyratory crusher. When the processed material is easy to crush and not very abrasive, an impact crusher may be the best choice for primary crushing.
One of the most important characteristics of a primary crusher is its capacity for accepting feed material without bridging. A large primary crusher is, naturally, more expensive than a smaller one. Therefore, the investment cost calculations for primary crushers are compared together against the total costs of primary stages, including quarry face clearing, blasting, and drilling costs. In many cases, dump trucks transport the rock to a stationary primary crusher. This may be an expensive solution. Amortization, fuel, tires, and maintenance costs can be included when the vehicles are in high demand. In modern aggregates operations, the use of mobile primary crushers that can move alongside the rock face is, in many cases, the most economical solution.
In terms of the size of the feed opening, the client gets a better return on investment when the primary crusher is a jaw crusher. That means less drilling and blasting because the crusher accepts larger boulders. The disadvantage of this type of crusher, when high capacity is required, is the relatively small discharge width, limiting the capacity as compared with the discharge circuit of a gyratory crusher. Jaw crushers are mainly used in plants producing up to approximately 1600 t/h.
The primary gyratory crusher offers high capacity thanks to its generously dimensioned circular discharge opening (which provides a much larger area than that of the jaw crusher) and the continuous operation principle (while the reciprocating motion of the jaw crusher produces a batch crushing action). The gyratory crusher has no rival in large plants with capacities starting from 1200 t/h and above. To have a feed opening corresponding to that of a jaw crusher, the primary gyratory crusher must be much taller and heavier. Also, primary gyratories require quite a massive foundation.
The primary impact crusher offers high capacity and is designed to accept large feed sizes. The primary impact crushers are used to process from 200 t/h up to 1900 t/h and feed sizes of up to 1830 mm (71") in the largest model. Primary impact crushers are generally used in nonabrasive applications and where the production of fines is not a problem. Of all primary crushers, the impactor is the crusher that gives the best cubical product.
If the intermediate crushing is done with the purpose of producing railway ballast, the quality of the product is important. In other cases, there normally are no quality requirements, except that the product be suitable for fine crushing.
Due to their design, cone crushers are generally a more expensive investment than impactors are. However, when correctly used, a cone crusher offers lower operating costs than a conventional impact crusher. Therefore, clients crushing hard or abrasive materials are advised to install cone crushers for the final crushing and cubicising stage.
Cone crushers can in most cases also give a good cubic shape to fine grades. They can be adapted to different applications. This is an important factor, as client-specific needs often change during a crushers lifetime.
The conventional type has horizontal shaft configuration, known as HSI. The other type consists of a centrifugal crusher with vertical shaft, generally known as VSI. Impactor operation is based on the principle of rapid transfer of impact energy to the rock material. Impactors produce cubic products, and they can offer high reduction ratios as long as the feed material is not too fine. This means that in certain cases it is possible to use a single impact crusher to carry out a task normally done in several crushing stages using compressing crushers (i.e., jaw, gyratory, and/or cone crushers). Impactors are mostly used for nonabrasive materials.
Conventional horizontal-shaft impact crushers are available in various sizes and models, from high-capacity primary crushers for large limestone quarries to specially designed machines for the crushing of materials such as slag.
There are two main categories of VSI crushers machines with impact wear parts around the body and machines that use a layer of accumulated material. The first type is in many respects similar to the conventional impactor with horizontal shaft and rotor. The second type became quite popular in the past decade and is known as the Barmac crusher. The difference between a conventional impactor and a VSI of the Barmac type is that the latter offers lower operating costs, but its reduction ratio is lower also. In a Barmac VSI, the material undergoes an intense rock-on-rock crushing process. In the other crushers, most of the reduction is done by the impact of stone against metal.
Customers operating old, rebuilt, or expanded plants often have problems with the shape of the product. In these cases, the addition of a Barmac VSI in the final crushing stage offers a solution to product shape problems.
The same applies to many mobile crushing units. As the number of crushing stages is normally small with this type of plant, it is almost impossible to obtain a good product shape unless the rock is relatively soft and thus more suited for the production of cubic product. A centrifugal crusher in the final stage can help to solve the problem.
Get the maximum potential out of your size reduction process to achieve improved crushing performance and lower cost per ton. By using our unique simulation software, our Chamber Optimization experts can design an optimized crushing chamber that matches the exact conditions under which you operate.
PE Jaw Crusher Jaw crusher is used for crushing all kinds of ores and rocks with compressive strength below 320MPa. It is generally used for primary crushing of materials. The machine is widely used in mining, building materials, metallurgy, electric power, water conservancy, transportation and many other fields.
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The compact FRITSCH Jaw Crusher PULVERISETTE 1 classic line is the ideal instrument for fast and effective pre-crushing of hard and very hard brittle materials - batchwise or continuous and even ferrous alloys are no problem for this instrument! Model I of the FRITSCH Jaw Crusher PULVERISETTE 1 classic line is ideal for a maximum feed size of 60 mm and a maximum continuous throughput of up to 140 kg/h depending on material and gap adjustment.
The powerful comminution of the sample takes place in the Jaw Crusher under high pressure between one fixed and one movable crushing jaw in an enclosed grinding chamber. The final fineness is easily set from the outside with the 10-stage adjustable gap between the crushing jaws. The ground sample automatically falls downward into a drawer for batchwise comminution or via a chute into a larger collection container for continuous operation or directly into a FRITSCH Disk Mill PULVERISETTE 13 classic line for further comminution.
The kinematics in other words, the movement between the movable and fixed crushing jaws of the FRITSCH Jaw Crusher PULVERISETTE 1 classic line can be easily adapted to the breaking characteristics of the respective sample: Select the upward and downward movement of the movable crushing jaw relative to the fixed one in order to receive a sample in a narrow particle size range. For a fast comminution, please select the nearly circular motion.
Safe and dust-free The closed grinding chamber with intervention protection of all moving parts and ensures a safe and dust-free operation. An integrated connection makes it very simple to combine the instrument with a dust exhaust system for automatic removal of the fine dust arising during grinding. The dust exhaust system is also very useful when cleaning grinding parts.
Easy to clean Due to the simple and quick releasing of the fixed crushing jaws the Jaw Crusher PULVERISETTE 1 classic line with just two hand motions it is quickly and thoroughly cleaned and offers an effective protection against cross contamination of your samples. Also, the funnel is particularly accessible, quickly and easily filled even with larger sample quantities and easy to clean. Its design enables the crushed material to be automatically conveyed into the crushing chamber blockages are practically impossible.
The crushing jaws and lateral support walls of the FRITSCH Jaw Crusher PULVERISETTE 1 classic line are available in 6 different materials in order to avoid undesired contamination due to material abrasion. The standard version is equipped with fixed and movable crushing jaws and support walls of made of hardened steel.View extensive accessories
For fast, continuous pre- and fine-grinding particularly of large quantities of coarse material, the combination of the FRITSCH Jaw crusher PULVERISETTE 1 classic line and the FRITSCH Disk Mill PULVERISETTE 13 classic line is the ideal solution. Mounted together onto a rack and connected to each other by a chute, they automatically grind the material from a particle size of up to 60 mm to a final fineness of down to 100 m fast, easy and effective in a single step! Read details about the Combination of Jaw Crusher PULVERISETTE 1 classic line and Disk Mill PULVERISETTE 13 classic line
From Boulder to Nano-Particles Medium-hard to hard materials with edge lengths up to 95 mm can be pre-crushed with the FRITSCH Jaw Crusher PULVERISETTE 1 so an additional fine comminution with many FRITSCH mills is possible. more information Crushing concrete coarsely and fine Concrete is a complex material, which its characteristics due to its composition and as a result of the systematic addition of additives can be adjusted very differentiated. However, this results in the demand to monitor this composition for two reasons: in order to ensure the desired useful properties and also to ensure the quality of the mixture. more information Salt, Sodium Chloride, Potassium Chloride A prerequisite for an efficient salt extraction and processing is the exact knowledge of the mineral compositions of in-situ evaporates, as well as their chemical composition and also of the accruing intermediate and final products during the manufacturing process. more information Pigment processing: The isolation of the naturally beautiful Mankind has always enjoyed enduring works of art. The particles of the pigments have always been playing a major role. For example, the oldest cave paintings still impress us today. One of the most renowned experts for the production of historical pigments is Dr. Kremer from Aichstetten (Bavaria, Germany). FRITSCH laboratory mills are of great importance in Dr. Kremer's pigment processing. more information Hydrolytic Class of Glass Packaging in all variations is an indispensable part of todays society. So it is implicit that almost every sold product is packaged. The materials from which the packaging is made are often viewed non-critical. But it is to be assumed that substances from packaging transfer into the wrapped product. Therefore an analysis of for example glass packaging is essential. more information
This type of crusher has a long history and belongs to traditional crushing equipment. Its motor drives the eccentric shaft to rotate via V-belt pulley and movable jaw to carry out a periodical complex pendular movement to generate crush capacity. There are two types: coarse crusher and fine crusher.
With the features like simple structure low price reliable operation and convenient adjustment of discharging opening it is very suitable for crushing the damp ore and the ore with a large content of clay with relatively coarse crushing grain size.
Since the end of the 19th century, jaw crusher has been used in ore crushing and aggregate processing industries for more than a hundred years. Rhythers PE Jaw Crusher is developed based on century-old accumulations. So, performances of PE Jaw Crusher is totally reliable.
Allowing for the operating conditions of jaw crushers are relatively severe and the quick-wear parts may be consumed rapidly, Rhyther thought deeply in selecting materials for core parts and adopted high-quality high-manganese steel casting which is most recognized in the world at present. This casting greatly extends the service life of core parts and effectively avoids too many shutdowns and maintenance tasks.
When materials which cannot be crushed fall into the jaw crusher and a load of crushing machine exceeds the normal level, the elbow plate designed by Rhyther can realize automatic fracturing and then stop the jaw crusher, thus avoiding the damage of the entire machine and guaranteeing the production safety.
Even though the structure of PE Jaw Crusher is relatively simple, all processing procedures require precise processing, for example: only precise machining, heat treatment and flaw inspection can guarantee the eccentric shaft to possess sufficient strength and rigidity; only precise blanking can guarantee the weights and structures of flywheel and grooved wheel to enhance the operating balance of the jaw crusher. For this purpose, Rhyther formulates strict quality inspection procedures and uses advanced machining equipment to deliver perfect jaw crushers.
Rhyther, whose businesses cover production and sales, takes responsibility for every machine produced by ourselves. We can offer customers technical services about products and original spare parts to ensure the worry-free operation.
The motor transmits power through belt, drives the moving jaw do periodic motion to the fixed jaw surround the eccentric shaft. The angle between toggle plate and moving jaw increases when moving jaw moves up. So the moving jaw closes to the fixed jaw, and the staff will be crushed in multiple ways. The angle of Jaw crusher between toggle plate and moving jaw decreases when moving jaw moves down, the moving jaw of jaw crusher moves away from fixed jaw by the pulling force of rod and spring, the products after crushing will be discharged from the outlet of Jaw crusher.
Jaw crusher and impact crusher are the main crushing equipments in the ore crushing production line. Jaw crusher is mainly used for the process of high hardness materials, mainly for the coarse crushing of ore, while the impact crusher for the treatment of medium hardness and brittleness stones, mainly for the medium crushing and fine crushing of stones.
Jaw crusher is mainly composed of frame, eccentric wheel, flywheel, moving jaw, side guard plate, elbow back seat, reset spring, fixed jaw plate and movable jaw plate etc. The jaw crusher uses power to drive the jaw plate to move periodically to extrude the material to achieve the crushing effect.
Impact crusher is mainly composed of reaction liner, feed port, plate hammer, rotor frame etc. When the impact crusher is working, the plate hammers that distributed on the rotor according to different rules will hit the material on the reaction liner for crushing.
a. Jaw crusher is a primary crusher, which is the first equipment to crush the raw stone. It has simple and reasonable structure, high hardness of wear-resistant parts, and is suitable for the primary crushing of high hardness stone;
b. Impact crusher is a two-stage crushing equipment, which is the equipment for crushing the discharged material of jaw crusher again. It is not suitable for crushing high hardness stone such as granite and basalt, and has good crushing effect for brittle and soft stone.
Jaw crusher is mainly used for crushing all kinds of ores and bulk materials into medium particle size and crushing materials whose compressive strength 320Mpa. The feed size of jaw crusher is 125mm 750mm, which is the preferred crushing equipment for primary crushing.
The feed size of the impact crusher 500mm and the compressive strength 350MPa. It is suitable for all kinds of coarse, medium and fine materials (granite, limestone, concrete, etc.). The discharge particle size can be adjusted and the crushing specifications are diversified.
a. When jaw crusher working, the motor drives the belt and pulley to move the moving jaw up and down through the eccentric shaft. When the moving jaw rises, the angle between the elbow plate and the moving jaw increases, so as to push the moving jaw plate close to the fixed jaw plate. At the same time, the material is crushed to achieve the purpose of crushing;
When the moving jaw goes down, the angle between the elbow plate and the moving jaw becomes smaller. Under the action of the pull rod and spring, the moving jaw plate leaves the fixed jaw plate. At this time, the crushed materials are discharged from the lower opening of the crushing chamber.
Under the action of centrifugal force, the materials will collide with the materials strongly that distributed around the turntable, and then break. After the two parts of materials collide and crush, they will form eddy current movement between the turntable and the shell, resulting in many times of friction and smashing. After many times of circulation crushing, they will be discharged from the discharge port.
a. Jaw crusher is coarse crushing equipment, the discharge size is generally large, and the size of finished product is generally 10-350mm; due to the crushing principle of jaw crusher, there are many needle and flake finished aggregate;
b. Impact crusher, as a medium and fine crushing equipment, has a finer discharging particle size; the impact crusher has the function of shaping, with good discharging particle shape of finished aggregate, less water chestnut angle, and the particle shape is better than the cone crusher.
a. Jaw crusher has a deep crushing cavity without dead zone, so it has a large crushing ratio, strong production capacity, simple and reasonable structure, reliable work, low operating cost, high efficiency in operation, environmental protection, large adjustment range of discharge port, which can meet the requirements of different demands;
b. Impact crusher has the advantages of large feed inlet, high crushing chamber, impact resistance and wear resistance, economic and reliable operation, strong crushing capacity, good comprehensive benefit, and the finished aggregate has uniform particle size, beautiful particle shape and good selling price;
c. The crushing efficiency of the jaw crusher is lower than impact crusher. Its because the jaw crusher does not work when discharging, but the rotor of the impact crusher keeps rotating, whenever the material enters the crushing chamber, it will be crushed.
In short, the production capacity of jaw crusher is larger than that of impact crusher. The output of jaw crusher can reach 600-800t per hour (depending on the different manufacturers and product model), and the output of impact crusher is about 260-450t per hour.
The sales of jaw crusher in the market is higher than that of impact crusher, the main reason is that the price of jaw crusher is more favorable. Secondly, jaw crusher is a more traditional crushing equipment, and its performance, quality, power consumption and other aspects can meet the application requirements of users, it is more cost-effective and easy to attract users attention
The Markwell Group, a plant and equipment hire provider based in Townsville, last year celebrated 40 years of business. Unfortunately the anniversary celebrations had to be put on hold because of COVID-19 but in spite of the pandemic, the business has this year continued to build on the foundations that were first established in 1980.
For almost its first two decades of operation, the family-owned business has been renowned for being North Queenslands largest earthmoving equipment hire specialist. The Markwell Group today offers dry hire equipment ranging from prime movers and body and water trucks through to quarry-spec wheel loaders, articulated dump trucks, graders and excavators, which in turn comprise a full array of attachments rock-breakers, augers, grabs, shears and pulverisers. It is a fleet that has come a long way, having started in 1980 and considering the companys first purchase was for a rock-breaking excavator in a project in Papua New Guinea (PNG) in 1989.
Twenty-three years ago, the Markwell Group diversified into the mobile crushing and screening market. We bought our first jaw crusher in February 1998, Gavin Markwell, the founder and managing director of Markwell Group, told Quarry. The business started as a mixture of contract crushing, dry hire and wet hire crushing units.
The contract crushing service today accounts for about 30 per cent of the Markwell Groups business. We generally campaign crush for other companies that is, quarries and mine sites that crush aggregates to road base to mining aggregates, Markwell explained.
We operate our own concrete crushing material, building pad material, roadbase, various aggregates. We do concrete crushing for a few of the shires in this region and we contract major quarries including Holcim, Boral, Hanson, as well as the smaller quarries. Were also at work in Bundaberg, Mount Isa and Cape York at the moment so within a 1000km radius of Townsville and occasionally work in PNG.
Markwell estimates that his company undertakes between 20 and 50 contract crushing jobs per year. However, the projects range from a few days to six months, he qualified. Many projects have run for a year. Our involvement in campaign crushing is either on sites where there are no crushing facilities at all or in quarries where extra assistance/extra production is required. Theyve won a large contract and they cant service their existing customers as well as complete the large contract, so we come into assist. Sometimes we may be asked to make specialty products.
Markwells contract crushing fleet currently comprises 15 mobile crushers (including cones, jaws, and impactors) and screens. Three of those machines are Kleemann mobile crushers: the MR130 Z Evo 2 Mobirex Impactor, the MCO9S Mobicone cone and the MC110 Z Mobicat jaw, all supplied by Wirtgen Australia, a member of the John Deere Group of companies. The MR 130 Z impactor and the MCO9S cone are equipped with recirculating screens, which Markwell said clip onto the back for quick release.
The MCO9S cone crusher has a large stroke for maximum crushing capacity that is powered by a powerful diesel-direct drive and regulated by a continuous feed system (CFS) that monitors the crusher fill level, load on the crusher drive, and crusher speed. The MCO9S is fitted with integrated overload and intelligent overload systems, a high performance secondary screening unit and a feeding conveyor which adapts to the fill level of the crusher, resulting in continuous optimal crusher level for maximum performance and a quality final product. From a maintenance perspective, cone liner change-outs are easy and brisk due to the fact of not having a backing compound meaning you will be back crushing sooner with less downtime. Other features include a sliding feed unit for fast set-up, a recirculating conveyor, a metal detector, automatic crusher gap setting and zero-point calculation, and an easy control touch panel that monitors speed, temperature, and pressure.
The MC110 Z features an extra-long articulated, flattened transition and highly raised crusher jaw, powered by a diesel-direct drive. It features an independent vibrating double-deck pre-screen, which offers effective screening of fine material for optimum final product. Like the MCO9S, it has a CFS which adapts the vibrating feeder and pre-screen frequencies to the crusher level, and a load reduction system (or LRS), which intervenes when the crusher is fed materials outside the permissible range. When the overload is reduced the system adapts to the highest possible output. It also features a crusher unblocking system for short downtimes, a by-pass flap for redirection of materials and a magnetic separator. A control touch panel monitors speed, temperature, and pressure.
The MC110 Z jaw and the MCO9S cone crushers are used by Markwell Group in quarrying applications, and at time of writing were assisting one of the larger quarrying producers in North Queensland. The MR 130 Z impact crusher is being used in concrete crushing and Markwell joked that it just loves eating concrete.
Like the MC110 Z jaw, the MR 130 Z features an independent vibrating double-deck pre-screen. It has a crusher inlet of 1300mm x 900mm and is equipped with a four-bar rotor with C-shaped blow bars for better impact over extended periods. Hydraulic gaps can be set via a touch screen and an integrated overload protection system prevents stoppages, material congestion and downtime. Like the other crushers, the MR 130 Z is fitted with a CFS. A lock and turn safety key transfer system allows work in certain areas only if they are mechanically locked. All components and functions can be controlled via a simple touch control system. The MR 130 Z is also equipped with a secondary screening unit and a magnetic separator to capture metals and sharps.
Markwell said the MR 130 Z impact crusher has impressed him because in concrete crushing applications it effectively doubles for both the cone and the jaw crushers. As he put it, the MR 130 Z essentially makes the same end product. Previously we made a -100mm product out of the jaw and then crushed that to a -23mm product through the cone. The impactor will go from the feed size of about 500mm to 600mm to -23mm with the use of the recirculating conveyor, in effect making the one product with one machine. It makes the site more efficient because there is one machine doing the job. This machine also has a 2.9m underpan feeder, which means less steel and contaminants are caught, and therefore less damage is done to the belt.
While he doesnt use it in quarrying specifically, Markwell said the MR 130 Z has crushed rock in addition to C&D materials and recycling. You dont use impactors in high silica contact rock, he explained. Its suitable for basalt and lime. You just have to pick what youre crushing.
One of the factors that persuaded Markwell to buy his Kleemann mobile trio was the fuel economy. He estimates his machines, which are three years old, would use about 30 per cent less fuel than the rest of his mobile fleet. For example, a 40-tonne impactor in Markwells inventory was consuming about 38 litres of fuel per hour compared to only 25 litres per hour on his 60-tonne MR 130 Z impactor.
David Dixon is the Kleemann sales manager in Queensland for Wirtgen Australia and has assisted Markwell Group with the set-up and ongoing maintenance of the Kleemann trio. He told Quarry that this fuel saving is common of the entire Kleemann mobile crushing suite.
The MR 130 Z impactor, the MCO9S cone and the MC110Z jaw have efficient and high performance diesel-direct drives for minimal fuel consumption per tonne of end product and high performance electric drives for chutes, screens and conveyors, Dixon explained. The generator runs the chutes, screens and conveyors, as opposed to the engine, which means theres less risk of hydraulic leaks, and low fuel consumption. Our entire crushing fleet, not just those three machines, has those features.
The other features of the machines are the continuous feed system the CFS and probes that monitor chamber depth, and when its crushing maintain a constant feed, maintain the belt, maintain a constant feed, Dixon added. The machine is running at its maximum efficiency all the time. Its operating non-stop and it will slow down and speed up accordingly where there are some stop-starts.
Another feature on the MR130 Z is optimal material flow, Dixon said, so its a straight feed, From the feeder to final end product belt the width increases incrementally meaning as material is crushed and bulks up it flows better through the machine. By total throughput, this helps with less fuel consumption, reduced life and less congestion.
Dixon described his role at Wirtgen Australia as an after sales and customer liaison. The sale doesnt just stop with the availability of the machine, he said. My background is in the general hire industry offering service on demand, 24/7.
His feedback is that Markwell Group is happy with the performance of the machine. Gavins feedback is positive, we answer his questions, we get back in a reasonable time frame, and nothing really is a problem with Wirtgen. We have quarterly meetings in Queensland, and we are constantly talking to Markwell about how we can improve our service to them.
As for those overdue 40th anniversary celebrations, Markwell joked that he still has memorabilia in stock that is now a year old. However, he is hoping to still organise a function in the near future that celebrates the milestone.Get in Touch with Mechanic